1. Field of the Invention
The invention relates to an operating condition determining system, an operating condition determining method, and a driving assist system, for determining operating conditions concerning operations performed by a driver of a vehicle.
2. Description of Related Art
A technology of assisting the driver in a driving operation in order to enhance the safety of the vehicle, such as an automobile, has been proposed. For example, a system that informs the driver of the presence of an obstacle or deviation of the vehicle from a running course, and a system that assists the driver in an operation to circumvent or avoid the obstacle or an operation to cause the vehicle to return to the course are known.
It is desirable that the systems as described above do not operate in response to vehicle behaviors caused by the driver's intentional operations. In Japanese Patent Application Publication No. 2006-515545 (JP-A-2006-515545), for example, it is proposed to determine that a lane change is made by the driver's intention when the steering angle exceeds a threshold value or the accelerator pedal operation amount (accelerator pedal stroke) exceeds a threshold value, and restrict the operation of the driving assist system.
In the meantime, the steering angle also changes when the turning angle of the wheels changes due to disturbances, such as the shape of the road surface and vibrations of the vehicle body. Also, when the running speed of the vehicle is high, the steering angle may be small even when a lane change is made by the intention of the driver. Thus, there is a possibility that an intentional driving operation of the driver is not correctly determined.